Compare and contrast wave summation with recruitment. How are they similar?

The combination of responses from a motor unit that has had two or more stimuli applied to it in quick succession. A motor unit of a muscle responds to a single stimulus with a simple twitch response. [ [ When a second stimulus is applied to the motor unit before the response to the first is completely lost, the two responses combine to produce a greater muscle tension than that produced by a

single response. If stimulation continues, the combination of the individual responses may result in tetanus. See also temporal summation. ] ]